Hiya
Im starting my CELTA in a few weeks so im starting to get my head around some grammar, and this is doing my head in at the moment.
OK, here´s two sentences:
-I have lived in New York since April (past perfect)
-I have been living in New York since April (past perfect continuous)
Neither of these strikes me as being grammatically incorrect, they seem to say exactly the same thing in a virtually identical way.
In this instance is it simply the case that either will do, or is one better than the other, and if so, why?
Cheers
Neilus

"In four minutes, I Will (future) have (aux=present) been (use of past participle) typing (continuously) for a half an hour", therefore future perfect continous.

in other words, the tense refers to something that began in the past (use of past participle "been"), is happening now (present use of aux "have"), and will end in the future (use of "will")... and finally it is a continuous activity (ergo "-ing")...

there is logic there somehow, i suggest you look at how aux and main verbs work, there is logic there somehow, and when you show that it is not magic to students (inter to advanced) they feel a lot more confident. Use a time-line, they can understand more easily that way.

Both sentences are grammatically correct, and both imply that I am still living in New York.

The difference in meaning is fairly subtle, with the present perfect imparting a sense that my residence in NY is now fairly permanent, and the present perfect continous implying that I am just a short-time resident.

Compare with simple present and present continuous:
- I live in London [it is my home].
- I am living in London [at the moment, but I may well move on soon, and I certainly don't consider it home].

This is a case of: It depends on the question and even then the answers wouldn't be the same. Why? Both are statements and in a sense don't reflect a real life conversational response when the subject and predicate are already implied; only the object of the question is required for a response. So it depends on the question if you are expected to make a statement out of your response.

EX. How long have you been living in New York?
TEFL answer: I have been living in New York since April.
Objective answer: Since April. /or Since last April.

EX. How long have you lived in New York?
TEFL answer: I have lived in New York since April.
Objective answer: Since April. /or Since last April.

Any teacher would beable to accept both as a statement. A computer administrated test: with test errors and out of context questions, questions that have nothing to do with TEFL and are basically TOEIC questions in disquise slipped into a TEFL test with 2 correct possible answers, one being more favored by the author of the test; is going to be unforgiving regardless of your English ability. So don't worry too much.
If your going to be answering a TEFL question; give them what they want for the sake of your test score. A statement using either tense stlye correctly.

If your going to be meeting people and making friends; answer in the objective so you don't sound like a casette taped played in ESL classrooms.

But seriously, either is fine if you are making a statement to someone first. The words 'lived' and 'been living' give the same meaning in the context of I as the subject; in relation to the preposition of time.